Banjo



Patented Sept. 28, 1920.

v1/mme M70/43% G. SANDSTROM.

BANJO.

APPLlcATIoN FILED Dsc. n.19

vGCEORGrE SANDSTROM, 0F OAKLAND, CALIFORNIA.

BANJO. Y

Specification of Letters Patent.

Patented Sept. 28, 1920.

Application led December 12, 1917. SeralNo. 206,746.

T0 all whom t may concern.'

Be it known that I, GEORGE SANDsrRoM, a citizen of the United States,residing at the city of Oakland, in the county of Alameda and State ofCalifornia,'have invented a new and useful Banjo, of which the followingis a specication.

My invention relates to improvements in tightening devices for banjoheads and other musical instrumentsl having peripheral resonating drumsor rims tob'e used in connection with a iexible vibrating head, and hasfor its object to provide a simple and easy method of tightening orrelaxing the flexible head.

Another object of my invention is the construction of a banjo head witha minimum amount of supporting material of a non* vibrating character,in contact with the resonating portions thereof.

A still further obj ect of my invention is to provide a tighteningdevice for flexible heads in musical instruments which may be quicklyand accurately adjusted to the desired tension by the operation of asmall number of simple parts.

lVith the above and other objects in view, I have invented the deviceillustrated in the accompanying drawings, in which Figure 1 is a rearelevation, showing a ring 4 in position with rim 1.

Fig. 2 is a section on line 2 2.

Fig. 3 is a sectional view of a portion of a side elevation of mydevice, enlarged to show the method of attaching brackets 11 to rim 1and the working combination of set` screw 6 and fiat rings 4 and 5.

Fig. 4 is a view partly in section, showing the wire fastener and theaction of the screws which tighten the resonating head.

Similar numerals refer to similar parts throughout the several views inthe drawings, in which 1 indicates my open resonating rim which has anannular shoulder 2 in its inside circumference designed to protect theedges of the flexible head 7; 8 is the neck and is shown only for thepurpose of making clear the manner in which rim 1 is attached thereto; 4is a flat ring made of any suitable material preferably of metal, havingan annular groove 10 in its outside circumference to receivea cord 8,and having a multiplicity of holes interiorly threaded to engage withthreaded set screws 6; 5 is a flat ring similar to 4, but having noholes or annular groove and when in position sets parallel to ring 4'; 6are set screws threaded to engage with the threads in the holes of ring4, with their points resting against the inside surface of ring 5 sothat their rotation from leftto right will press the two rings apart; isa flexible head of suitable shape and material-which is litted over theouter circumference of ring' 5" and has its edges drawn down and fittedunder cord 8 in groove 10; 9 are the two ends of cord bound together andholding flexible head 7 in place; l1 are brackets which are rigidlyattached at their rear ends to the inside surface of ring 5 and havetheir front ends rigidly attached to the inside surface of rim 1 byscrews 12; 13 is a rivet passing through the rear end of brackets 11 andring 5 and lirmly attaching the two together.

To operate my device, a head of flexible material of a kind usuallyemployed in the making of banjo heads, is fitted over the outside ofring 5 to which has been rigidly affixed the brackets 11, and its outeredges are drawn over and brought beneath cord S in groove 10 in theouter circumference of ring 4; rings 4 and 5 are thus brought into aparallel position with their flat surfaces facing each other. The setscrews 6 are then screwed into the holes made to receive them in ring 4until the points of the said set screws are brought into Contact withthe inside surface of ring 5; the parts thus held together by theflexible head '7 are pressed into position in rim 1 and the brackets 11are attached to the inside circumference of the said rim 1, by screwsl2. To stretch the flexible head to the desired tension, set screws 6are rotated to the right and the ring 4, having the outer edges of thesaid head firmly held to it by cord 8, is drawn away from the said ring5 by the pressure of the points of the said set screws 6 against theinside surface of the said ring 5.

Having now described my invention, that which l claim to be new anddesire to procure by Letters Patent is:

1. A tightening device for banjo heads and other musical instrumentshaving an open rim, a flexible head interposed within the opening of thesaid rim, an annular lip integral with the said rim and projectinginwardly from the top thereof, a fiat top ring fixedly attached by screw13 and by bracket 11, to the inside circumference of the said rim overwhich the said head is drawn, a bottom flat ring interposed parallel tothe said top ring and having in its outside circumference an annulargroove, a cord embedded therein, the outer edge of the said flexiblehead passing within the said groove and being firmly held by the saidcord; a

ring provided with holes and interiorly threaded, a multiplicity of setscrews in the rim, a flat top ring iixedly attached as shown, to theinside circumference of the said rim over which the said head is drawn;a bottom flat ring interposed parallel tothe said top ring, and havingin its outer circumference an annular groove, Va cord or cable Vadaptedto engage with the said groove, the outer edge of the said flexible phead being passed between the said groove and the said cable; aY ringprovided with holes and interiorly threaded, a multiplicity of setscrews in the said holes and engaging the threads thereof and the pointsof the said set screws resting on the lower surface of the said toplring, by means of which the said flexible head is pressed firmlystbantially as described.

GEORGE 'SANDSTROML against the annular lip in thesaid rim, sub-

